Lead screw drive for grinding machines



Aug. 15, 1933. s w BATH 1,922,520

LEAD SCREW DRIVE FOR GRINDING MACHINES Filed March 27, 1951 3 Sheets-Sheet l Aug. 15, 1933- s. w. BATH LEAD SCREW DRIVE FOR GRINDING MACHINES 3 Sheets-Sheet 2 Filed March 27, 1931 M? El EHIHIIIHHI 3 1205]? 7, Eat/a. fwa tfi w Aug. 15, 1933. s w BATH 1,922,520

LEAD SCREW DRIVE FOR GRINDING MACHINES Patented Aug. 15, 1933 UNITED STATES LEAD SCREW DRIVE FOR GRINDING MACHINES Stanley W. Bath, Shrewsbury, Mass, assignor, by mesne assignments, to John Bath & Company, Worcester, Mass, a Corporation of Massachusetts Application March 2'7, 1931.

10 Claims.

This invention relates to grinding machines in which the work is supported on a work slide which is reciprocated by means of a lead screw mounted thereon and engaging a nut fixed in relation to the bed or frame of the machine.

It is the general object of my invention to provide improved driving connections between the work spindle and the lead screw in a ginding machine of this defined type.

My invention further relates to grinding machines in which the work spindle is supported on a rocking table by movement of which the work may be relieved, and also relates to grinding machines in which the work spindle is supported on a table which is mounted to swivel on the work slide.

A further object of my invention is to provide positive driving connections between the work spindle and the lead screw, adapted by adjustment to continue operative when the work table is swiveled on the work slide, and also adapted to maintain a substantially constant speed re lation between the work spindle and the lead screw, even when the work spindle swings toward and from the grinding wheel to relieve the work.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawings, in which Fig. 1 is a detail front elevation showing one method of driving the work in my improved grinding machine;

Fig. 2 is a plan view of the work head of my improved grinding machine;

Fig. 3 is a sectional end elevation, taken along the line 3-3 in Fig. 2;

Fig. 4 is a front elevation, looking in the direction of the arrow 4 in Fig. 2;

Fig. 5 is a detail sectional front elevation, taken along the line 5-5 in Fig. 2;

Fig. 6 is a front elevation of the driving connection between the work spindle. and the lead screw;

Fig. 7 is an end elevation, looking in the direction of the arrow 7 in Fig. 6,

Fig. 8 is a detail plan view, looking in the direction or the arrow 8 in Fig 6. and

Fig. 9 is a detail front elevation to be de scribed.

Referring to the drawings, I have shown portions of a grinding machine in which a grind Serial No. 525,849

ing wheel G (Fig. 1) is rotatably mounted to engage the peripheral surface of a piece of work W supported on a head center 10 and a tail center 11.

The head or live center 10 is mounted in a work spindle 12 which is rotatable in hearings in a head stock 14. The tail center 11 is mounted in the usual tail stock 15. The head stock 14 and tail stock 15 are mounted for axial adjustment on suitable guiding 16 and 17 on a rocking table 20 (Fig. 3) which is pivotally mounted on a rock shaft 21 supported in bearings 22 on a swivel table 23.

Relieving cams 24 are mounted on a shaft 25 rotatable in bearings at the side of the head 14 and connected by gears 26, 27 and 28 to the work spindle 12. A cam roll 30 (Fig. 3) is mounted in a stand 31 and is adjustable lengthwise of the swivel table 23 to position the roll 30 under any desired cam 24. The cams 24 are rotated in timed relation to the rotation of the work spindle l2 and of the work W supported and driven thereby.

As the cams 24 rotate, the rocking table 20 and the work supported thereon is moved toward and away from the grinding wheel G a desired number of times during each revolution of the work, thereby relieving the lands of a tap or producing a similar effect upon other pieces of work. The cams 24 may be made of different throws or with diflerent numbers of rises, so as to vary either the frequency or the extent of the oscillating movement of the work toward and from the grinding wheel.

The work spindle 12 may be rotated in any convenient manner as by a worm 32 (Fig. 3) mounted on a drive shaft 33 and engaging a worm wheel 34 (Fig. 5), loosely mounted to ro-. tate about the axis of the work spindle 12 and adapted to be connected thereto by a manually operated clutch collar 35. The shaft 33 may be driven through a flexible connection 36 (Fig. 2) or in any other convenient manner.

One or more relatively heavy springs 37 (Fig. 3) hold the selected cam 24 firmly seated against the cam roll 30. The work W may be driven by a dog 38 and driver 39 (Fig. 1) or by any other suitable driving connections. Instead of the work centers 10 and 11, the work W' may obviously be supported in a chuck mounted in the usual manner on the work spindle 12.

The gears 26, 27 and 28 constitute change gears by which the speed ratio between the work spindle and the cam shaft 25 may be varied. An additional gear 40 (Fig. 2) is mounted alongside iii) relative thereto.

the gear 28 and the gears 26 and 2'7 may be offset on their supports to engage the gear rather than the gear 28, thereby giving additional gear ratios when necessary.

The swivel table 23 is pivoted at 450: (Fig. 9) to a work slide and is provided with a segmental slot 43 (Fig. 2) through which a bolt 44 extends into the work slide 45 on which the swivel table 23 is supported. Suitable graduations 46 (Fig. 2) are provided for determining the angular position of the swivel table relative to the work slide and these two parts may be secured together by tightening the clamping screws 44, a similar screw being provided at the foot stock end of the table.

The parts thus far described are substantially" similar to the construction shown and described in the copending application of Ernest A. Walker, Serial No. 523,802, filed March 19, 1931, and in themselves form no part of my present invention which will now be described. I

A lead screw 50 (Fig. 6) is rotatably mounted in bearings 51 on the under side of the work slide 45 and engages a nut 52 mounted in fixed relation to the base or bed 53 (Fig. '7) on which the work slide 45 is mounted to slide along suit able supporting surfaces 54 and 55.

The lead screw 50 is connected by bevel gears 56 and 57 to an upright shaft 58, supported in bearings 59 and 60 formed on brackets extending outward from the end of the work slide 45.

A second or upper vertical shaft 62 is mounted in bearings 63 and 64 on a stand 65 carried by the swivel table 23. The shaft 62 is connected by bevel gears 67 and 68 to a horizontal shaft 70 supported in a bearing '71. The bearing '71 is carried by the stand 65 on the swivel table 23, previously described. 7

A hearing '72 is formed on a member '73 (Fig. 8) rotatably mounted on the rocking table 20 to swing about the axis of the shaft 12. A bevel gear '74 is keyed to the shaft '70 and is slidable This bevel gear '74 is rotatably supported in the bearing 72'- and engages the bevel gear '75 on the outer end of the work spindle 12. This extended portion of the spindle 12 is supported in an extended bearing or bearings '76 (Fig. 8') in the stand 73 upon the rocking table 20.

The driving connection between the upper vertical shaft 62 and the lower vertical shaft 58- comprises a-gear (Fig. 6) on the lower end of the shaft 62, a gear 32 on the upper end of the shaft 58, and a pair of gears 83 and 84 secured together and rotatable on a bearing stud 85 on a block 86 adjustable along a radial guideway 88 in an arm 90. The arm 90 is pivoted to swing about the axis of the shaft 62 and its bearing 63 and may be firmly secured in any desired angular position.

When the swivel table 23 is aligned with the work slide 45, for grinding straight cylindrical work, the vertical shafts 58 and 62 are in axial alignment and the arm 90 is adjusted to extend straight parallel to the guideways of the work slide 45. The block 86 is then moved inward until the gears 83 and 84 engage the gears 80 and 82 respectively, thus forming a positive geared driving connection between the shafts 62 and 58.

If the swivel table 23 is set at an angle to the work slide 45, the arm 90 is swung about the axis of the shaft 62 until a position is reached in which the gears 83 and 84 mesh accurately with the gears 80 and 82, in which position the arm 90 and sliding block 86 are then secured.

I have thus provided a positive geared driving connection between the work spindle 12 and lead screw 50, which is operative in every angular adjustment of the swivel table 23.

' The geared connections described also provide for the rocking movement of the table 20. It will be remembered that the gear 74 on the horizontal shaft '70 moves back and forth with the rocking of the table 20, whereas the shaft 70- and gear 68 are supported on the stand 65 carried by'the swivel table 23 and consequently do not partake of this rocking movement. However, the gear 2 4 is keyed and slidable on the shaft '70, so that the only effect of the rocking movement of the table 20 is to slide the gear '74 back and forth a few thousandths of an inch along the shaft '70 but without producing any perceptible change in the relative speeds of rotation of the spindle 12 and shaft '70.

This is a very substantial improvement over constructions previously used in which the drive from the spindle to the lead screw was through an ordinary gear train. When such a gear train was used, the swinging of the work spindle toward and from the grinding wheel increased the rate of angular movement of the lead screw as the work swung in one direction and slowed down the angular movement of the lead screw as the work swung in the opposite direction. This caused an irregular angular movement of the lead screw and produced minute but definite irregularities or dwells in the work.

Accordingly, it will appear that I have provided a positive geared driving connection between the work spindle 12 and the lead screw 58, so designed and constructed that the connection may be adjusted for any angular setting of the swivel table 23 and also so designed that the speed relation between the shaft 12 and lead screw 50 will remain practically constant, regardless of the rocking of the table 20.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:-

1. In a grinding machine, a work slide, a work table swiveled thereon, a head stock and work spindle on said work table, a lead screw mounted in bearings carried by said work slide, and a geared driving connection between said work spindle and said lead screw, connection comprising a vertical shaft mounted on said swivel table, a second vertical shaft mounted on said work slide, and an adjustable drive between said two shafts by which a positive drive may be effected in different relative positions of said tables.

2. In a grinding machine, a work slide, a work table swiveled thereon, ahead stock and work spindle on said work-table, a lead screw mounted in bearings carried by said work slide, and a geared, driving connection between said work spindle and said lead screw, said connection comprising a vertical shaft mounted on said swivel table, a second vertical shaft mounted on said work slide, gears on said shafts, a supporting arm mounted to swing about the axis of one of said shafts, a pair of gears secured together, and a bearing for said gears slidably adjustable on said arm to engage said. pair of gears with said first mentioned gears in diiferent angular relations of said table and slide.

3. In a grinding machine, a work slide, a work table swiveled thereon, a head stock and work spindle on said work table, a lead screw mounted in bearings carried by said work slide, and a geared driving connection between said work spindle and said lead screw, said connection comprising a vertical shaft mounted on said'swivel table, a second vertical shaft mounted on said work slide, gears on the adjacent ends of said vertical shafts, a supporting arm mounted to swing about the axis of one of said shafts, a guideway in said arm radial of said shaft, a bearing member slidable in said guideway, and gears mounted on said bearing member and engageable with said first mentioned gears in different relative adjusted positions of said table and slide.

4. In a grinding machine, a grinding wheel, a work slide, a rocking table mounted to swing about an axis substantially longitudinal of said work slide, means to rock said table, a head stock and work spindle on said rocking table, a lead screw mounted in bearings carried by said work slide, and a geared driving connection between said work spindle and said lead screw by which said lead screw is rotated in substantially uniform speed relation to the work spindle as the work-supporting table is rocked on the work slide toward and from the grinding wheel, said connection including a driving shaft and a driving member keyed to and slidable axially thereon, one of said last-named parts being mounted on said work slide and the other on said rocking table and said parts having relative axial sliding movement as the table is rocked.

5. In a grinding machine, a work slide, a table swivelled thereon, a rocking table mounted on said swivel table to swing about an axis substantially longitudinal of said swivel table, means to rock said rocking table, a head stock and work spindle on said rocking table, a lead screw mounted in bearings carried by said work slide, and a geared driving connection between said work spindle and said lead screw, said connection including upper and lower vertical shafts, one of which is mounted on the work slide and the other on the swivel table, the ends of said shafts being adjacent each other, a positive gear drive between said two shafts, and a telescoping gear connection between the upper vertical shaft and the work spindle.

6. In a grinding machine, a grinding wheel, a Work slide, a rocking table mounted to swing about an axis substantially longitudinal of said work slide, means to rock said table, a head stock and work spindle on said rocking table, a lead screw mounted in bearings carried by said work slide, and a geared driving connection between said work spindle and said lead screw, said connection comprising a gear mounted in a stand on said rocking table and rotated in definite speed relation with said work spindle, the swinging movement of the work toward and from the grinding wheel being substantially along the axis of said gear, a shaft for said gear mounted in bearings fixed in relation to said work slide, said gear being keyed and slidable on said shaft, and a positive driving connection from said shaft to said lead screw.

7. The combination in a lead screw drive in a grinding machine as set forth in claim 6, in which the shaft for the slidable gear is substantially horizontal and extends transversely of the work slide at a point substantially above said work slide, and in which the shaft is substantially in the plane of the swinging movement of the work spindle toward and from the grinding wheel.

8. The combination in a lead screw drive in a grinding machine as set forth in claim 6, in which the shaft for the slidable gear is substantially horizontal and extends transversely of the work slide at a point substantially above said work slide, and in which said positive driving connection includes transmission mechanism revolvable about a substantially vertical axis between said horizontal transverse shaft and said lead screw.

9. The combination in a lead screw drive in a grinding machine as set forth in claim 6, in which the shaft for the slidable gear is substantially horizontal and extends transversely of the work slide at a point substantially above said work slide, and in which said positive driving connection includes a two-part vertical shaft, the two parts thereof being adjustable horizontally out of axial alignment with each other, and an adjustable gear connection between the two parts of said vertical shaft by which a positive driving connection may be maintained when said shafts are out of axial alignment with each other,

10. In a grinding machine, a grinding wheel, a work slide, a swivel table on said work slide, a rocking table mounted to swing about an axis longitudinal of said swivel table, means to rock said table, a head stock and work spindle on said rocking table, a lead screw carried by said work slide, a lower vertical shaft on said work slide geared to said lead screw, an upper vertical shaft on said swivel table, gearing adjustable to connect said vertical shafts in each adjusted position of said swivel table on said work slide, a horizontal shaft on said swivel table geared to said upper vertical shaft, and a rotatable driving member mounted on said rocking table, geared to said work spindle, and slidable but not rotatable relative to said horizontal shaft.

STANLEY W. BATH. 

